Turbo

Turbo, or turbocharging, referred to as T, was first used in the automotive field by the Swedish Saab (SAAB) automobile company. Many people now know that turbocharging is abbreviated as TURBO. If you see TURBO or T on the rear of a car, it means that the engine used in the car is a turbocharged engine. For example, Volkswagen Bora's 1.8T, Passat's 1.8T, Audi's 2.0T, etc. The engines of these cars work by burning fuel in the engine cylinder to produce power. When the engine displacement is certain, if you want to increase the engine's output power, the most effective way is to provide more fuel for combustion. However, it is easy to provide more fuel into the cylinder, but it is difficult to provide a sufficient amount of air to support complete combustion of the fuel with a traditional engine air intake system.

Take the working principle of a gasoline engine as an example. For every kilogram of gasoline supplied to the cylinder, approximately 15 kilograms of air need to be sucked into the cylinder to ensure full combustion of the gasoline. However, the volume of these 15 kilograms of air will be very large. It is not easy to completely inhale such a large volume of air just by relying on the vacuum generated by the cylinder during the engine intake process. Therefore, it is particularly important to improve the engine's ability to inhale gas, that is, to improve the engine's charging efficiency. Supercharging technology is a method of increasing the air intake capacity of the engine. In principle, it uses a special compressor to pre-compress the gas before entering the cylinder, increase the density of the gas entering the cylinder, and reduce the volume of the gas. In this way, the mass of the gas per unit volume is greatly increased. The amount of air intake can meet the combustion needs of fuel, thereby achieving the purpose of increasing engine power. The compressor used in the supercharging process is also called a supercharger.

The engine supercharging method can basically be divided into three categories according to the different energy sources used to drive the supercharger:

1. The first type is a mechanical supercharging system, which increases The compressor is directly driven by the engine crankshaft through a gear (or chain, etc.).

2. The second type is the exhaust gas turbocharging system. The supercharger is driven by the exhaust gas discharged when the engine is working.

3. The third category is the compound supercharging system, which uses both an exhaust gas turbocharger and a mechanically driven supercharger on the engine. In addition, there are other boosting methods such as inertial boosting and air wave boosting.

Propeller

The ancient wheel, the so-called "paddle wheel" in Europe, cooperates with the steam engine by mounting a row of straight blades of the original paddle wheel diagonally on a rotating hub. It constitutes the prototype of a propeller;

2. Ancient windmills can output torque when rotating with the wind. On the contrary, in the water, input torque to rotate the windmill, and the water windmill may propel the ship;

3. At that time, the Archimedes screw pump, which had been used for centuries, could lift water horizontally or vertically. The fact that the screw structure could pump water was an important inspiration as a propeller.

The great British scientist Hooke successfully used the principle of anemometers to measure water flow in 1683. At the same time, he proposed a new propeller - the Hooke propeller (Figure 1) Propelling ships and making significant contributions to ship propellers.

In 1752, Swiss physicist Bernoulli made the first report that propellers were superior to various propellers that existed before it. He designed a propeller with a double-lead screw, installed forward of the stern rudder. In 1764, Swiss mathematician Euler studied other propellers that could replace sails, such as paddle wheels (paddle wheels). The water spray also includes the propeller.

Submersibles and submarines move under the water. Traditional paddles and sails cannot be used, and heavy and bulky paddle wheels are also difficult to adapt to. So the first manual propeller was not used on a ship, but as a propulsion tool for submersibles.

The advent of the steam engine provided new and good power for ship propellers. Propulsors conformed to the development of steam engines and became the latest topic in ship propulsion.

The first person to experiment with power-driven propellers was the American Stephen. In 1804, he built a 7.6-meter-long boat, driven directly by a steam engine, and made the first attempt on the Hudson River. During the experimental voyage, it was found that the engine was not working, so it was replaced with a Watt steam engine. The experimental speed was 4 knots, and the maximum speed reached 8 knots.

The Stephen propeller has four windmill-style blades (Figure 2), which are forged. Compared with ordinary windmills, it increases the radial width of the blades, allowing the pitch and speed to be selected in the experiment. For better coordination, the blades are made into a structure with adjustable pitch. During the two weeks of trial sailing on the Hudson River, the propeller changed several pitch values, but the experimental results were not ideal, and the performance was far inferior to that of the paddle wheel. This experiment made him understand that under the low-speed conditions of a steam engine, the advantages of the paddle wheel were fully exerted, and it was an inevitable conclusion that its propulsion efficiency was higher than that of the propeller.

The introduction of the Archimedes propeller was first seen in 1803. In 1829, there was a British patent for the Archimedes propeller. On this basis, some civilian propellers were built in 1840-1841. In 1843, the British Navy replaced the paddle wheel with a propeller for the first time on the HMS Ratterer. Later, Smith designed 20 propeller ships and participated in the war with Russia. Smith became a famous figure.

In 1843, the U.S. Navy built the first propeller ship "Princeton". It was designed by Captain Ericsson. Under Ericson's active promotion, the United States built it one after another. It has built 41 civilian propeller ships, with the largest displacement reaching 2,000 tons.

Although the United Kingdom, the United States and other countries have achieved some success, there are still many problems when propellers are used for ship propulsion, such as terrible vibrations on wooden-hulled ships, propeller shaft bearing wear below the waterline, and propeller shaft Seals, thrust bearings, etc.

With the advancement of technology, the above-mentioned defects of propellers have been overcome one by one, and the speed of steam engines has increased, more and more propellers have replaced paddle wheels on ships. By 1858, the "Great Eastern" was equipped with the largest propeller in the world at that time, with a diameter of 7.3 meters, a weight of 36 tons, and a rotation speed of 50 revolutions per minute. At that time, propeller standards were no longer authoritative. Since the propulsion efficiency of the propeller is close to that of the paddle wheel, and it has many advantages that the paddle wheel cannot compete with, the paddle wheel gradually disappears on sea ships.

In the development of science and technology, many mechanical devices have been widely used before people knew the performance of them. However, it is difficult for these devices to achieve their optimal performance before people fully understand its physical laws and complete theoretical analysis. The propeller was no exception. Until 1860, although it had become unique on sea ships, its achievements were all based on years of accumulated experience. The progress of propellers relies only on the intuitive reasoning of experts, which can no longer meet the development needs of ship technology. It requires scientists to provide a complete explanation of its hydrodynamic characteristics, which has prompted the development of propeller theory.

Theoretical research on propellers has done more than any other professional field in the development of ship technology, transitioning from empirical methods to digital design, and then applying computer technology to optimize propeller design. Varied. The design of a good propeller is very important, and model testing also plays a major role.

The development of modern propellers has made little contribution since my country became a semi-colony in the mid-19th century. After liberation, my country's shipbuilding industry has achieved new development, and a lot of design and research work has been carried out on propeller technology, and various types of ships have been equipped with a large number of self-designed and manufactured propellers. What is most worthy of pride is the advent of the "Guandao propeller", which is a major creation in the development of propeller technology in my country. It was in the 1960s. There was a master named Zhou Ting at Guangzhou Wenchong Shipyard. Based on his decades of experience in making propellers, he made the outline of the propeller blades into the style of Guan Gong's 82-pound sword in the Romance of the Three Kingdoms. , he vividly called it "Guandao Paddle" (Figure 4).

The "Guandao paddle" has been tested on some ships, which has increased the speed of the ship. What is even more surprising is that the vibration of the spiral has been greatly weakened.

It was used on the Yangtze River 2,000-horsepower tugboats and Chinese-character landing craft at that time, and achieved good results. This achievement attracted many people in the shipbuilding industry. In 1973, the first open-water test study of the "Guandao Paddle" was conducted in Shanghai, and a design drawing was also provided. What’s interesting is that the “highly inclined” propellers developed today in the world’s famous shipbuilding countries, such as (Figure 5) the latest large inclined propeller for ships, have a diameter of 6.3 meters, a shaft power of 35,660 kilowatts, and a ship speed of 32.8 knots. ; Figure 6 shows the latest large-skew propeller used on passenger ferries. The propeller has a diameter of 5.1 meters, a shaft power of 15,640 dry watts, and a ship speed of 23.2 knots. Figure 7 shows the large side-inclined propeller used on the latest chemical ship. The propeller has a diameter of 6.2 meters, a shaft power of 10,400 kilowatts, and a ship speed of 16.7 knots. They are very similar to "Guandao paddles", and their important features are vibration and low noise, which are also the characteristics of "Guandao paddles".